Microstructure and Corrosion Resistance of 2205 Stainless Steel Weld by CO₂ Gas-Shielded Arc Welding with Flux-Cored Wire

The CO₂ gas-shielded arc welding with a flux-cored wire was carried out on 2205 duplex stainless steel plate with a set of optimized welding parameters. The microstructure and corrosion resistance of the weld and the base metal were studied. The results show that the weld and the base metal were both composed of a duplex microstructure of ferrite and austenite, and had similar volume fractions of ferrite, which was 42.4% and 49.5%, respectively. The pitting corrosion rates of the weld and the base metal increased with the rise of FeCl₃ solution concentration and temperature during immersion corrosion in FeCl₃ solutions. The weld had higher pitting corrosion rates than the base metal, indicating the weld had poorer corrosion resistance. The free corrosion potential, capacitive radius and passive film resistance of the weld were all lower than those of the base metal, indicating the corrosion resistance of the weld was lower. However, the nucleation resistance of the weld during corrosion was large, leading to an uneasy extension of the corrosion pit.